/* pngread.c - read a PNG file
 *
 * Last changed in libpng 1.4.1 [February 25, 2010]
 * Copyright (c) 1998-2010 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 *
 * This file contains routines that an application calls directly to
 * read a PNG file or stream.
 */

#include "png.h"
#define PNG_NO_PEDANTIC_WARNINGS
#ifdef PNG_READ_SUPPORTED
    #include "pngpriv.h"


/* Create a PNG structure for reading, and allocate any memory needed. */
png_structp PNGAPI
png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr,
                       png_error_ptr error_fn, png_error_ptr warn_fn)
{

    #ifdef PNG_USER_MEM_SUPPORTED
    return (png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
                                     warn_fn, NULL, NULL, NULL));
}

/* Alternate create PNG structure for reading, and allocate any memory
 * needed.
 */
png_structp PNGAPI
png_create_read_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
                         png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
                         png_malloc_ptr malloc_fn, png_free_ptr free_fn)
{
    #endif /* PNG_USER_MEM_SUPPORTED */

    #ifdef PNG_SETJMP_SUPPORTED
    volatile
    #endif
    png_structp png_ptr;
    volatile int png_cleanup_needed = 0;

    #ifdef PNG_SETJMP_SUPPORTED
    #ifdef USE_FAR_KEYWORD
    jmp_buf jmpbuf;
    #endif
    #endif

    int i;

    png_debug(1, "in png_create_read_struct");

    #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
                                               malloc_fn, mem_ptr);
    #else
    png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
    #endif
    if (png_ptr == NULL)
        return (NULL);

    /* Added at libpng-1.2.6 */
    #ifdef PNG_USER_LIMITS_SUPPORTED
    png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
    png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
    #ifdef PNG_USER_CHUNK_CACHE_MAX
    /* Added at libpng-1.2.43 and 1.4.0 */
    png_ptr->user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
    #endif
    #ifdef PNG_SET_USER_CHUNK_MALLOC_MAX
    /* Added at libpng-1.2.43 and 1.4.1 */
    png_ptr->user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
    #endif
    #endif

    #ifdef PNG_SETJMP_SUPPORTED
    /* Applications that neglect to set up their own setjmp() and then
       encounter a png_error() will longjmp here.  Since the jmpbuf is
       then meaningless we abort instead of returning. */
    #ifdef USE_FAR_KEYWORD
    if (setjmp(jmpbuf))
    #else
    if (setjmp(png_jmpbuf(png_ptr))) /* Sets longjmp to match setjmp */
    #endif
        PNG_ABORT();
    #ifdef USE_FAR_KEYWORD
    png_memcpy(png_jmpbuf(png_ptr), jmpbuf, png_sizeof(jmp_buf));
    #endif
    #endif /* PNG_SETJMP_SUPPORTED */

    #ifdef PNG_USER_MEM_SUPPORTED
    png_set_mem_fn(png_ptr, mem_ptr, malloc_fn, free_fn);
    #endif

    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);

    if (user_png_ver)
    {
        i = 0;
        do
        {
            if (user_png_ver[i] != png_libpng_ver[i])
                png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
        }
        while (png_libpng_ver[i++]);
    }
    else
        png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;


    if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
    {
        /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
         * we must recompile any applications that use any older library version.
         * For versions after libpng 1.0, we will be compatible, so we need
         * only check the first digit.
         */
        if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
            (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
            (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
        {
            #ifdef PNG_STDIO_SUPPORTED
            char msg[80];
            if (user_png_ver)
            {
                png_snprintf(msg, 80,
                             "Application was compiled with png.h from libpng-%.20s",
                             user_png_ver);
                png_warning(png_ptr, msg);
            }
            png_snprintf(msg, 80,
                         "Application  is  running with png.c from libpng-%.20s",
                         png_libpng_ver);
            png_warning(png_ptr, msg);
            #endif
            #ifdef PNG_ERROR_NUMBERS_SUPPORTED
            png_ptr->flags = 0;
            #endif
            png_warning(png_ptr,
                        "Incompatible libpng version in application and library");

            png_cleanup_needed = 1;
        }
    }

    if (!png_cleanup_needed)
    {
        /* Initialize zbuf - compression buffer */
        png_ptr->zbuf_size = PNG_ZBUF_SIZE;
        png_ptr->zbuf = (png_bytep)png_malloc_warn(png_ptr,
                                                   png_ptr->zbuf_size);
        if (png_ptr->zbuf == NULL)
            png_cleanup_needed = 1;
    }
    png_ptr->zstream.zalloc = png_zalloc;
    png_ptr->zstream.zfree = png_zfree;
    png_ptr->zstream.opaque = (voidpf)png_ptr;

    if (!png_cleanup_needed)
    {
        switch (inflateInit(&png_ptr->zstream))
        {
            case Z_OK: /* Do nothing */ break;
            case Z_MEM_ERROR:
            case Z_STREAM_ERROR: png_warning(png_ptr, "zlib memory error");
                png_cleanup_needed = 1; break;
            case Z_VERSION_ERROR: png_warning(png_ptr, "zlib version error");
                png_cleanup_needed = 1; break;
            default: png_warning(png_ptr, "Unknown zlib error");
                png_cleanup_needed = 1;
        }
    }

    if (png_cleanup_needed)
    {
        /* Clean up PNG structure and deallocate any memory. */
        png_free(png_ptr, png_ptr->zbuf);
        png_ptr->zbuf = NULL;
        #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)png_ptr,
                             (png_free_ptr)free_fn, (png_voidp)mem_ptr);
        #else
        png_destroy_struct((png_voidp)png_ptr);
        #endif
        return (NULL);
    }

    png_ptr->zstream.next_out = png_ptr->zbuf;
    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

    png_set_read_fn(png_ptr, NULL, NULL);


    return (png_ptr);
}


    #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the information before the actual image data.  This has been
 * changed in v0.90 to allow reading a file that already has the magic
 * bytes read from the stream.  You can tell libpng how many bytes have
 * been read from the beginning of the stream (up to the maximum of 8)
 * via png_set_sig_bytes(), and we will only check the remaining bytes
 * here.  The application can then have access to the signature bytes we
 * read if it is determined that this isn't a valid PNG file.
 */
void PNGAPI
png_read_info(png_structp png_ptr, png_infop info_ptr)
{
    png_debug(1, "in png_read_info");

    if (png_ptr == NULL || info_ptr == NULL)
        return;

    /* If we haven't checked all of the PNG signature bytes, do so now. */
    if (png_ptr->sig_bytes < 8)
    {
        png_size_t num_checked = png_ptr->sig_bytes,
                   num_to_check = 8 - num_checked;

        #ifdef PNG_IO_STATE_SUPPORTED
        png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
        #endif

        png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
        png_ptr->sig_bytes = 8;

        if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
        {
            if (num_checked < 4 &&
                png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
                png_error(png_ptr, "Not a PNG file");
            else
                png_error(png_ptr, "PNG file corrupted by ASCII conversion");
        }
        if (num_checked < 3)
            png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
    }

    for (;;)
    {
        PNG_IHDR;
        PNG_IDAT;
        PNG_IEND;
        PNG_PLTE;
        #ifdef PNG_READ_bKGD_SUPPORTED
        PNG_bKGD;
        #endif
        #ifdef PNG_READ_cHRM_SUPPORTED
        PNG_cHRM;
        #endif
        #ifdef PNG_READ_gAMA_SUPPORTED
        PNG_gAMA;
        #endif
        #ifdef PNG_READ_hIST_SUPPORTED
        PNG_hIST;
        #endif
        #ifdef PNG_READ_iCCP_SUPPORTED
        PNG_iCCP;
        #endif
        #ifdef PNG_READ_iTXt_SUPPORTED
        PNG_iTXt;
        #endif
        #ifdef PNG_READ_oFFs_SUPPORTED
        PNG_oFFs;
        #endif
        #ifdef PNG_READ_pCAL_SUPPORTED
        PNG_pCAL;
        #endif
        #ifdef PNG_READ_pHYs_SUPPORTED
        PNG_pHYs;
        #endif
        #ifdef PNG_READ_sBIT_SUPPORTED
        PNG_sBIT;
        #endif
        #ifdef PNG_READ_sCAL_SUPPORTED
        PNG_sCAL;
        #endif
        #ifdef PNG_READ_sPLT_SUPPORTED
        PNG_sPLT;
        #endif
        #ifdef PNG_READ_sRGB_SUPPORTED
        PNG_sRGB;
        #endif
        #ifdef PNG_READ_tEXt_SUPPORTED
        PNG_tEXt;
        #endif
        #ifdef PNG_READ_tIME_SUPPORTED
        PNG_tIME;
        #endif
        #ifdef PNG_READ_tRNS_SUPPORTED
        PNG_tRNS;
        #endif
        #ifdef PNG_READ_zTXt_SUPPORTED
        PNG_zTXt;
        #endif
        png_uint_32 length = png_read_chunk_header(png_ptr);
        PNG_CONST png_bytep chunk_name = png_ptr->chunk_name;

        /* This should be a binary subdivision search or a hash for
         * matching the chunk name rather than a linear search.
         */
        if (!png_memcmp(chunk_name, png_IDAT, 4))
            if (png_ptr->mode & PNG_AFTER_IDAT)
                png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;

        if (!png_memcmp(chunk_name, png_IHDR, 4))
            png_handle_IHDR(png_ptr, info_ptr, length);
        else if (!png_memcmp(chunk_name, png_IEND, 4))
            png_handle_IEND(png_ptr, info_ptr, length);
        #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
        else if (png_handle_as_unknown(png_ptr, chunk_name))
        {
            if (!png_memcmp(chunk_name, png_IDAT, 4))
                png_ptr->mode |= PNG_HAVE_IDAT;
            png_handle_unknown(png_ptr, info_ptr, length);
            if (!png_memcmp(chunk_name, png_PLTE, 4))
                png_ptr->mode |= PNG_HAVE_PLTE;
            else if (!png_memcmp(chunk_name, png_IDAT, 4))
            {
                if (!(png_ptr->mode & PNG_HAVE_IHDR))
                    png_error(png_ptr, "Missing IHDR before IDAT");
                else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                         !(png_ptr->mode & PNG_HAVE_PLTE))
                    png_error(png_ptr, "Missing PLTE before IDAT");
                break;
            }
        }
        #endif
        else if (!png_memcmp(chunk_name, png_PLTE, 4))
            png_handle_PLTE(png_ptr, info_ptr, length);
        else if (!png_memcmp(chunk_name, png_IDAT, 4))
        {
            if (!(png_ptr->mode & PNG_HAVE_IHDR))
                png_error(png_ptr, "Missing IHDR before IDAT");
            else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                     !(png_ptr->mode & PNG_HAVE_PLTE))
                png_error(png_ptr, "Missing PLTE before IDAT");

            png_ptr->idat_size = length;
            png_ptr->mode |= PNG_HAVE_IDAT;
            break;
        }
        #ifdef PNG_READ_bKGD_SUPPORTED
        else if (!png_memcmp(chunk_name, png_bKGD, 4))
            png_handle_bKGD(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_cHRM_SUPPORTED
        else if (!png_memcmp(chunk_name, png_cHRM, 4))
            png_handle_cHRM(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_gAMA_SUPPORTED
        else if (!png_memcmp(chunk_name, png_gAMA, 4))
            png_handle_gAMA(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_hIST_SUPPORTED
        else if (!png_memcmp(chunk_name, png_hIST, 4))
            png_handle_hIST(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_oFFs_SUPPORTED
        else if (!png_memcmp(chunk_name, png_oFFs, 4))
            png_handle_oFFs(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_pCAL_SUPPORTED
        else if (!png_memcmp(chunk_name, png_pCAL, 4))
            png_handle_pCAL(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sCAL_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sCAL, 4))
            png_handle_sCAL(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_pHYs_SUPPORTED
        else if (!png_memcmp(chunk_name, png_pHYs, 4))
            png_handle_pHYs(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sBIT_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sBIT, 4))
            png_handle_sBIT(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sRGB_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sRGB, 4))
            png_handle_sRGB(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_iCCP_SUPPORTED
        else if (!png_memcmp(chunk_name, png_iCCP, 4))
            png_handle_iCCP(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sPLT_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sPLT, 4))
            png_handle_sPLT(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_tEXt_SUPPORTED
        else if (!png_memcmp(chunk_name, png_tEXt, 4))
            png_handle_tEXt(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_tIME_SUPPORTED
        else if (!png_memcmp(chunk_name, png_tIME, 4))
            png_handle_tIME(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_tRNS_SUPPORTED
        else if (!png_memcmp(chunk_name, png_tRNS, 4))
            png_handle_tRNS(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_zTXt_SUPPORTED
        else if (!png_memcmp(chunk_name, png_zTXt, 4))
            png_handle_zTXt(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_iTXt_SUPPORTED
        else if (!png_memcmp(chunk_name, png_iTXt, 4))
            png_handle_iTXt(png_ptr, info_ptr, length);
        #endif
        else
            png_handle_unknown(png_ptr, info_ptr, length);
    }
}
    #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

/* Optional call to update the users info_ptr structure */
void PNGAPI
png_read_update_info(png_structp png_ptr, png_infop info_ptr)
{
    png_debug(1, "in png_read_update_info");

    if (png_ptr == NULL)
        return;
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
        png_read_start_row(png_ptr);
    else
        png_warning(png_ptr,
                    "Ignoring extra png_read_update_info() call; row buffer not reallocated");

    png_read_transform_info(png_ptr, info_ptr);
}

    #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Initialize palette, background, etc, after transformations
 * are set, but before any reading takes place.  This allows
 * the user to obtain a gamma-corrected palette, for example.
 * If the user doesn't call this, we will do it ourselves.
 */
void PNGAPI
png_start_read_image(png_structp png_ptr)
{
    png_debug(1, "in png_start_read_image");

    if (png_ptr == NULL)
        return;
    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
        png_read_start_row(png_ptr);
}
    #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

    #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
void PNGAPI
png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
{
    PNG_IDAT;
    PNG_CONST int png_pass_dsp_mask[7] = { 0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
                                           0xff };
    PNG_CONST int png_pass_mask[7] = { 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff };
    int ret;

    if (png_ptr == NULL)
        return;

    png_debug2(1, "in png_read_row (row %lu, pass %d)",
               (unsigned long)png_ptr->row_number, png_ptr->pass);

    if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
        png_read_start_row(png_ptr);
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
        /* Check for transforms that have been set but were defined out */
        #if defined (PNG_WRITE_INVERT_SUPPORTED) && !defined (PNG_READ_INVERT_SUPPORTED)
        if (png_ptr->transformations & PNG_INVERT_MONO)
            png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
        #endif
        #if defined (PNG_WRITE_FILLER_SUPPORTED) && !defined (PNG_READ_FILLER_SUPPORTED)
        if (png_ptr->transformations & PNG_FILLER)
            png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
        #endif
        #if defined (PNG_WRITE_PACKSWAP_SUPPORTED) && \
        !defined (PNG_READ_PACKSWAP_SUPPORTED)
        if (png_ptr->transformations & PNG_PACKSWAP)
            png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
        #endif
        #if defined (PNG_WRITE_PACK_SUPPORTED) && !defined (PNG_READ_PACK_SUPPORTED)
        if (png_ptr->transformations & PNG_PACK)
            png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
        #endif
        #if defined (PNG_WRITE_SHIFT_SUPPORTED) && !defined (PNG_READ_SHIFT_SUPPORTED)
        if (png_ptr->transformations & PNG_SHIFT)
            png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
        #endif
        #if defined (PNG_WRITE_BGR_SUPPORTED) && !defined (PNG_READ_BGR_SUPPORTED)
        if (png_ptr->transformations & PNG_BGR)
            png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
        #endif
        #if defined (PNG_WRITE_SWAP_SUPPORTED) && !defined (PNG_READ_SWAP_SUPPORTED)
        if (png_ptr->transformations & PNG_SWAP_BYTES)
            png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
        #endif
    }

    #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* If interlaced and we do not need a new row, combine row and return */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
        switch (png_ptr->pass)
        {
            case 0:
                if (png_ptr->row_number & 0x07)
                {
                    if (dsp_row != NULL)
                        png_combine_row(png_ptr, dsp_row,
                                        png_pass_dsp_mask[png_ptr->pass]);
                    png_read_finish_row(png_ptr);
                    return;
                }
                break;
            case 1:
                if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
                {
                    if (dsp_row != NULL)
                        png_combine_row(png_ptr, dsp_row,
                                        png_pass_dsp_mask[png_ptr->pass]);
                    png_read_finish_row(png_ptr);
                    return;
                }
                break;
            case 2:
                if ((png_ptr->row_number & 0x07) != 4)
                {
                    if (dsp_row != NULL && (png_ptr->row_number & 4))
                        png_combine_row(png_ptr, dsp_row,
                                        png_pass_dsp_mask[png_ptr->pass]);
                    png_read_finish_row(png_ptr);
                    return;
                }
                break;
            case 3:
                if ((png_ptr->row_number & 3) || png_ptr->width < 3)
                {
                    if (dsp_row != NULL)
                        png_combine_row(png_ptr, dsp_row,
                                        png_pass_dsp_mask[png_ptr->pass]);
                    png_read_finish_row(png_ptr);
                    return;
                }
                break;
            case 4:
                if ((png_ptr->row_number & 3) != 2)
                {
                    if (dsp_row != NULL && (png_ptr->row_number & 2))
                        png_combine_row(png_ptr, dsp_row,
                                        png_pass_dsp_mask[png_ptr->pass]);
                    png_read_finish_row(png_ptr);
                    return;
                }
                break;
            case 5:
                if ((png_ptr->row_number & 1) || png_ptr->width < 2)
                {
                    if (dsp_row != NULL)
                        png_combine_row(png_ptr, dsp_row,
                                        png_pass_dsp_mask[png_ptr->pass]);
                    png_read_finish_row(png_ptr);
                    return;
                }
                break;
            case 6:
                if (!(png_ptr->row_number & 1))
                {
                    png_read_finish_row(png_ptr);
                    return;
                }
                break;
        }
    }
    #endif

    if (!(png_ptr->mode & PNG_HAVE_IDAT))
        png_error(png_ptr, "Invalid attempt to read row data");

    png_ptr->zstream.next_out = png_ptr->row_buf;
    png_ptr->zstream.avail_out =
        (uInt)(PNG_ROWBYTES(png_ptr->pixel_depth,
                            png_ptr->iwidth) + 1);
    do
    {
        if (!(png_ptr->zstream.avail_in))
        {
            while (!png_ptr->idat_size)
            {
                png_crc_finish(png_ptr, 0);

                png_ptr->idat_size = png_read_chunk_header(png_ptr);
                if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
                    png_error(png_ptr, "Not enough image data");
            }
            png_ptr->zstream.avail_in = (uInt)png_ptr->zbuf_size;
            png_ptr->zstream.next_in = png_ptr->zbuf;
            if (png_ptr->zbuf_size > png_ptr->idat_size)
                png_ptr->zstream.avail_in = (uInt)png_ptr->idat_size;
            png_crc_read(png_ptr, png_ptr->zbuf,
                         (png_size_t)png_ptr->zstream.avail_in);
            png_ptr->idat_size -= png_ptr->zstream.avail_in;
        }
        ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
        if (ret == Z_STREAM_END)
        {
            if (png_ptr->zstream.avail_out || png_ptr->zstream.avail_in ||
                png_ptr->idat_size)
                png_benign_error(png_ptr, "Extra compressed data");
            png_ptr->mode |= PNG_AFTER_IDAT;
            png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
            break;
        }
        if (ret != Z_OK)
            png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
                      "Decompression error");

    }
    while (png_ptr->zstream.avail_out);

    png_ptr->row_info.color_type = png_ptr->color_type;
    png_ptr->row_info.width = png_ptr->iwidth;
    png_ptr->row_info.channels = png_ptr->channels;
    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
    png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
                                              png_ptr->row_info.width);

    if (png_ptr->row_buf[0])
        png_read_filter_row(png_ptr, &(png_ptr->row_info),
                            png_ptr->row_buf + 1, png_ptr->prev_row + 1,
                            (int)(png_ptr->row_buf[0]));

    png_memcpy(png_ptr->prev_row, png_ptr->row_buf, png_ptr->rowbytes + 1);

    #ifdef PNG_MNG_FEATURES_SUPPORTED
    if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
    {
        /* Intrapixel differencing */
        png_do_read_intrapixel(&(png_ptr->row_info), png_ptr->row_buf + 1);
    }
    #endif


    if (png_ptr->transformations || (png_ptr->flags & PNG_FLAG_STRIP_ALPHA))
        png_do_read_transformations(png_ptr);

    #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Blow up interlaced rows to full size */
    if (png_ptr->interlaced &&
        (png_ptr->transformations & PNG_INTERLACE))
    {
        if (png_ptr->pass < 6)
            /* Old interface (pre-1.0.9):
             * png_do_read_interlace(&(png_ptr->row_info),
             *    png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
             */
            png_do_read_interlace(png_ptr);

        if (dsp_row != NULL)
            png_combine_row(png_ptr, dsp_row,
                            png_pass_dsp_mask[png_ptr->pass]);
        if (row != NULL)
            png_combine_row(png_ptr, row,
                            png_pass_mask[png_ptr->pass]);
    }
    else
    #endif
    {
        if (row != NULL)
            png_combine_row(png_ptr, row, 0xff);
        if (dsp_row != NULL)
            png_combine_row(png_ptr, dsp_row, 0xff);
    }
    png_read_finish_row(png_ptr);

    if (png_ptr->read_row_fn != NULL)
        (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
}
    #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

    #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read one or more rows of image data.  If the image is interlaced,
 * and png_set_interlace_handling() has been called, the rows need to
 * contain the contents of the rows from the previous pass.  If the
 * image has alpha or transparency, and png_handle_alpha()[*] has been
 * called, the rows contents must be initialized to the contents of the
 * screen.
 *
 * "row" holds the actual image, and pixels are placed in it
 * as they arrive.  If the image is displayed after each pass, it will
 * appear to "sparkle" in.  "display_row" can be used to display a
 * "chunky" progressive image, with finer detail added as it becomes
 * available.  If you do not want this "chunky" display, you may pass
 * NULL for display_row.  If you do not want the sparkle display, and
 * you have not called png_handle_alpha(), you may pass NULL for rows.
 * If you have called png_handle_alpha(), and the image has either an
 * alpha channel or a transparency chunk, you must provide a buffer for
 * rows.  In this case, you do not have to provide a display_row buffer
 * also, but you may.  If the image is not interlaced, or if you have
 * not called png_set_interlace_handling(), the display_row buffer will
 * be ignored, so pass NULL to it.
 *
 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
 */

void PNGAPI
png_read_rows(png_structp png_ptr, png_bytepp row,
              png_bytepp display_row, png_uint_32 num_rows)
{
    png_uint_32 i;
    png_bytepp rp;
    png_bytepp dp;

    png_debug(1, "in png_read_rows");

    if (png_ptr == NULL)
        return;
    rp = row;
    dp = display_row;
    if (rp != NULL && dp != NULL)
        for (i = 0; i < num_rows; i++)
        {
            png_bytep rptr = *rp++;
            png_bytep dptr = *dp++;

            png_read_row(png_ptr, rptr, dptr);
        }
    else if (rp != NULL)
        for (i = 0; i < num_rows; i++)
        {
            png_bytep rptr = *rp;
            png_read_row(png_ptr, rptr, NULL);
            rp++;
        }
    else if (dp != NULL)
        for (i = 0; i < num_rows; i++)
        {
            png_bytep dptr = *dp;
            png_read_row(png_ptr, NULL, dptr);
            dp++;
        }
}
    #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

    #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the entire image.  If the image has an alpha channel or a tRNS
 * chunk, and you have called png_handle_alpha()[*], you will need to
 * initialize the image to the current image that PNG will be overlaying.
 * We set the num_rows again here, in case it was incorrectly set in
 * png_read_start_row() by a call to png_read_update_info() or
 * png_start_read_image() if png_set_interlace_handling() wasn't called
 * prior to either of these functions like it should have been.  You can
 * only call this function once.  If you desire to have an image for
 * each pass of a interlaced image, use png_read_rows() instead.
 *
 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
 */
void PNGAPI
png_read_image(png_structp png_ptr, png_bytepp image)
{
    png_uint_32 i, image_height;
    int pass, j;
    png_bytepp rp;

    png_debug(1, "in png_read_image");

    if (png_ptr == NULL)
        return;

    #ifdef PNG_READ_INTERLACING_SUPPORTED
    pass = png_set_interlace_handling(png_ptr);
    #else
    if (png_ptr->interlaced)
        png_error(png_ptr,
                  "Cannot read interlaced image -- interlace handler disabled");
    pass = 1;
    #endif


    image_height = png_ptr->height;
    png_ptr->num_rows = image_height; /* Make sure this is set correctly */

    for (j = 0; j < pass; j++)
    {
        rp = image;
        for (i = 0; i < image_height; i++)
        {
            png_read_row(png_ptr, *rp, NULL);
            rp++;
        }
    }
}
    #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

    #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the end of the PNG file.  Will not read past the end of the
 * file, will verify the end is accurate, and will read any comments
 * or time information at the end of the file, if info is not NULL.
 */
void PNGAPI
png_read_end(png_structp png_ptr, png_infop info_ptr)
{
    png_debug(1, "in png_read_end");

    if (png_ptr == NULL)
        return;
    png_crc_finish(png_ptr, 0); /* Finish off CRC from last IDAT chunk */

    do
    {
        PNG_IHDR;
        PNG_IDAT;
        PNG_IEND;
        PNG_PLTE;
        #ifdef PNG_READ_bKGD_SUPPORTED
        PNG_bKGD;
        #endif
        #ifdef PNG_READ_cHRM_SUPPORTED
        PNG_cHRM;
        #endif
        #ifdef PNG_READ_gAMA_SUPPORTED
        PNG_gAMA;
        #endif
        #ifdef PNG_READ_hIST_SUPPORTED
        PNG_hIST;
        #endif
        #ifdef PNG_READ_iCCP_SUPPORTED
        PNG_iCCP;
        #endif
        #ifdef PNG_READ_iTXt_SUPPORTED
        PNG_iTXt;
        #endif
        #ifdef PNG_READ_oFFs_SUPPORTED
        PNG_oFFs;
        #endif
        #ifdef PNG_READ_pCAL_SUPPORTED
        PNG_pCAL;
        #endif
        #ifdef PNG_READ_pHYs_SUPPORTED
        PNG_pHYs;
        #endif
        #ifdef PNG_READ_sBIT_SUPPORTED
        PNG_sBIT;
        #endif
        #ifdef PNG_READ_sCAL_SUPPORTED
        PNG_sCAL;
        #endif
        #ifdef PNG_READ_sPLT_SUPPORTED
        PNG_sPLT;
        #endif
        #ifdef PNG_READ_sRGB_SUPPORTED
        PNG_sRGB;
        #endif
        #ifdef PNG_READ_tEXt_SUPPORTED
        PNG_tEXt;
        #endif
        #ifdef PNG_READ_tIME_SUPPORTED
        PNG_tIME;
        #endif
        #ifdef PNG_READ_tRNS_SUPPORTED
        PNG_tRNS;
        #endif
        #ifdef PNG_READ_zTXt_SUPPORTED
        PNG_zTXt;
        #endif
        png_uint_32 length = png_read_chunk_header(png_ptr);
        PNG_CONST png_bytep chunk_name = png_ptr->chunk_name;

        if (!png_memcmp(chunk_name, png_IHDR, 4))
            png_handle_IHDR(png_ptr, info_ptr, length);
        else if (!png_memcmp(chunk_name, png_IEND, 4))
            png_handle_IEND(png_ptr, info_ptr, length);
        #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
        else if (png_handle_as_unknown(png_ptr, chunk_name))
        {
            if (!png_memcmp(chunk_name, png_IDAT, 4))
            {
                if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
                    png_benign_error(png_ptr, "Too many IDATs found");
            }
            png_handle_unknown(png_ptr, info_ptr, length);
            if (!png_memcmp(chunk_name, png_PLTE, 4))
                png_ptr->mode |= PNG_HAVE_PLTE;
        }
        #endif
        else if (!png_memcmp(chunk_name, png_IDAT, 4))
        {
            /* Zero length IDATs are legal after the last IDAT has been
             * read, but not after other chunks have been read.
             */
            if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
                png_benign_error(png_ptr, "Too many IDATs found");
            png_crc_finish(png_ptr, length);
        }
        else if (!png_memcmp(chunk_name, png_PLTE, 4))
            png_handle_PLTE(png_ptr, info_ptr, length);
        #ifdef PNG_READ_bKGD_SUPPORTED
        else if (!png_memcmp(chunk_name, png_bKGD, 4))
            png_handle_bKGD(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_cHRM_SUPPORTED
        else if (!png_memcmp(chunk_name, png_cHRM, 4))
            png_handle_cHRM(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_gAMA_SUPPORTED
        else if (!png_memcmp(chunk_name, png_gAMA, 4))
            png_handle_gAMA(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_hIST_SUPPORTED
        else if (!png_memcmp(chunk_name, png_hIST, 4))
            png_handle_hIST(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_oFFs_SUPPORTED
        else if (!png_memcmp(chunk_name, png_oFFs, 4))
            png_handle_oFFs(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_pCAL_SUPPORTED
        else if (!png_memcmp(chunk_name, png_pCAL, 4))
            png_handle_pCAL(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sCAL_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sCAL, 4))
            png_handle_sCAL(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_pHYs_SUPPORTED
        else if (!png_memcmp(chunk_name, png_pHYs, 4))
            png_handle_pHYs(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sBIT_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sBIT, 4))
            png_handle_sBIT(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sRGB_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sRGB, 4))
            png_handle_sRGB(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_iCCP_SUPPORTED
        else if (!png_memcmp(chunk_name, png_iCCP, 4))
            png_handle_iCCP(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_sPLT_SUPPORTED
        else if (!png_memcmp(chunk_name, png_sPLT, 4))
            png_handle_sPLT(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_tEXt_SUPPORTED
        else if (!png_memcmp(chunk_name, png_tEXt, 4))
            png_handle_tEXt(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_tIME_SUPPORTED
        else if (!png_memcmp(chunk_name, png_tIME, 4))
            png_handle_tIME(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_tRNS_SUPPORTED
        else if (!png_memcmp(chunk_name, png_tRNS, 4))
            png_handle_tRNS(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_zTXt_SUPPORTED
        else if (!png_memcmp(chunk_name, png_zTXt, 4))
            png_handle_zTXt(png_ptr, info_ptr, length);
        #endif
        #ifdef PNG_READ_iTXt_SUPPORTED
        else if (!png_memcmp(chunk_name, png_iTXt, 4))
            png_handle_iTXt(png_ptr, info_ptr, length);
        #endif
        else
            png_handle_unknown(png_ptr, info_ptr, length);
    }
    while (!(png_ptr->mode & PNG_HAVE_IEND));
}
    #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

/* Free all memory used by the read */
void PNGAPI
png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
                        png_infopp end_info_ptr_ptr)
{
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL, end_info_ptr = NULL;
    #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn = NULL;
    png_voidp mem_ptr = NULL;
    #endif

    png_debug(1, "in png_destroy_read_struct");

    if (png_ptr_ptr != NULL)
        png_ptr = *png_ptr_ptr;
    if (png_ptr == NULL)
        return;

    #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
    mem_ptr = png_ptr->mem_ptr;
    #endif

    if (info_ptr_ptr != NULL)
        info_ptr = *info_ptr_ptr;

    if (end_info_ptr_ptr != NULL)
        end_info_ptr = *end_info_ptr_ptr;

    png_read_destroy(png_ptr, info_ptr, end_info_ptr);

    if (info_ptr != NULL)
    {
        #ifdef PNG_TEXT_SUPPORTED
        png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, -1);
        #endif

        #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn,
                             (png_voidp)mem_ptr);
        #else
        png_destroy_struct((png_voidp)info_ptr);
        #endif
        *info_ptr_ptr = NULL;
    }

    if (end_info_ptr != NULL)
    {
        #ifdef PNG_READ_TEXT_SUPPORTED
        png_free_data(png_ptr, end_info_ptr, PNG_FREE_TEXT, -1);
        #endif
        #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)end_info_ptr, (png_free_ptr)free_fn,
                             (png_voidp)mem_ptr);
        #else
        png_destroy_struct((png_voidp)end_info_ptr);
        #endif
        *end_info_ptr_ptr = NULL;
    }

    if (png_ptr != NULL)
    {
        #ifdef PNG_USER_MEM_SUPPORTED
        png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
                             (png_voidp)mem_ptr);
        #else
        png_destroy_struct((png_voidp)png_ptr);
        #endif
        *png_ptr_ptr = NULL;
    }
}

/* Free all memory used by the read (old method) */
void /* PRIVATE */
png_read_destroy(png_structp png_ptr, png_infop info_ptr,
                 png_infop end_info_ptr)
{
    #ifdef PNG_SETJMP_SUPPORTED
    jmp_buf tmp_jmp;
    #endif
    png_error_ptr error_fn;
    png_error_ptr warning_fn;
    png_voidp error_ptr;
    #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn;
    #endif

    png_debug(1, "in png_read_destroy");

    if (info_ptr != NULL)
        png_info_destroy(png_ptr, info_ptr);

    if (end_info_ptr != NULL)
        png_info_destroy(png_ptr, end_info_ptr);

    png_free(png_ptr, png_ptr->zbuf);
    png_free(png_ptr, png_ptr->big_row_buf);
    png_free(png_ptr, png_ptr->prev_row);
    png_free(png_ptr, png_ptr->chunkdata);
    #ifdef PNG_READ_QUANTIZE_SUPPORTED
    png_free(png_ptr, png_ptr->palette_lookup);
    png_free(png_ptr, png_ptr->quantize_index);
    #endif
    #ifdef PNG_READ_GAMMA_SUPPORTED
    png_free(png_ptr, png_ptr->gamma_table);
    #endif
    #ifdef PNG_READ_BACKGROUND_SUPPORTED
    png_free(png_ptr, png_ptr->gamma_from_1);
    png_free(png_ptr, png_ptr->gamma_to_1);
    #endif
    if (png_ptr->free_me & PNG_FREE_PLTE)
        png_zfree(png_ptr, png_ptr->palette);
    png_ptr->free_me &= ~PNG_FREE_PLTE;
    #if defined (PNG_tRNS_SUPPORTED) || \
    defined (PNG_READ_EXPAND_SUPPORTED) || defined (PNG_READ_BACKGROUND_SUPPORTED)
    if (png_ptr->free_me & PNG_FREE_TRNS)
        png_free(png_ptr, png_ptr->trans_alpha);
    png_ptr->free_me &= ~PNG_FREE_TRNS;
    #endif
    #ifdef PNG_READ_hIST_SUPPORTED
    if (png_ptr->free_me & PNG_FREE_HIST)
        png_free(png_ptr, png_ptr->hist);
    png_ptr->free_me &= ~PNG_FREE_HIST;
    #endif
    #ifdef PNG_READ_GAMMA_SUPPORTED
    if (png_ptr->gamma_16_table != NULL)
    {
        int i;
        int istop = (1 << (8 - png_ptr->gamma_shift));
        for (i = 0; i < istop; i++)
        {
            png_free(png_ptr, png_ptr->gamma_16_table[i]);
        }
        png_free(png_ptr, png_ptr->gamma_16_table);
    }
    #ifdef PNG_READ_BACKGROUND_SUPPORTED
    if (png_ptr->gamma_16_from_1 != NULL)
    {
        int i;
        int istop = (1 << (8 - png_ptr->gamma_shift));
        for (i = 0; i < istop; i++)
        {
            png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
        }
        png_free(png_ptr, png_ptr->gamma_16_from_1);
    }
    if (png_ptr->gamma_16_to_1 != NULL)
    {
        int i;
        int istop = (1 << (8 - png_ptr->gamma_shift));
        for (i = 0; i < istop; i++)
        {
            png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
        }
        png_free(png_ptr, png_ptr->gamma_16_to_1);
    }
    #endif
    #endif
    #ifdef PNG_TIME_RFC1123_SUPPORTED
    png_free(png_ptr, png_ptr->time_buffer);
    #endif

    inflateEnd(&png_ptr->zstream);
    #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    png_free(png_ptr, png_ptr->save_buffer);
    #endif

    #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    #ifdef PNG_TEXT_SUPPORTED
    png_free(png_ptr, png_ptr->current_text);
    #endif /* PNG_TEXT_SUPPORTED */
    #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */

    /* Save the important info out of the png_struct, in case it is
     * being used again.
     */
    #ifdef PNG_SETJMP_SUPPORTED
    png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
    #endif

    error_fn = png_ptr->error_fn;
    warning_fn = png_ptr->warning_fn;
    error_ptr = png_ptr->error_ptr;
    #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
    #endif

    png_memset(png_ptr, 0, png_sizeof(png_struct));

    png_ptr->error_fn = error_fn;
    png_ptr->warning_fn = warning_fn;
    png_ptr->error_ptr = error_ptr;
    #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr->free_fn = free_fn;
    #endif

    #ifdef PNG_SETJMP_SUPPORTED
    png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof(jmp_buf));
    #endif

}

void PNGAPI
png_set_read_status_fn(png_structp png_ptr, png_read_status_ptr read_row_fn)
{
    if (png_ptr == NULL)
        return;
    png_ptr->read_row_fn = read_row_fn;
}


    #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
        #ifdef PNG_INFO_IMAGE_SUPPORTED
void PNGAPI
png_read_png(png_structp png_ptr, png_infop info_ptr,
             int transforms,
             voidp params)
{
    int row;

    if (png_ptr == NULL)
        return;

    /* png_read_info() gives us all of the information from the
     * PNG file before the first IDAT (image data chunk).
     */
    png_read_info(png_ptr, info_ptr);
    if (info_ptr->height > PNG_UINT_32_MAX / png_sizeof(png_bytep))
        png_error(png_ptr, "Image is too high to process with png_read_png()");

    /* -------------- image transformations start here ------------------- */

    #ifdef PNG_READ_16_TO_8_SUPPORTED
    /* Tell libpng to strip 16 bit/color files down to 8 bits per color.
     */
    if (transforms & PNG_TRANSFORM_STRIP_16)
        png_set_strip_16(png_ptr);
    #endif

    #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
    /* Strip alpha bytes from the input data without combining with
     * the background (not recommended).
     */
    if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
        png_set_strip_alpha(png_ptr);
    #endif

    #if defined (PNG_READ_PACK_SUPPORTED) && !defined (PNG_READ_EXPAND_SUPPORTED)
    /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
     * byte into separate bytes (useful for paletted and grayscale images).
     */
    if (transforms & PNG_TRANSFORM_PACKING)
        png_set_packing(png_ptr);
    #endif

    #ifdef PNG_READ_PACKSWAP_SUPPORTED
    /* Change the order of packed pixels to least significant bit first
     * (not useful if you are using png_set_packing).
     */
    if (transforms & PNG_TRANSFORM_PACKSWAP)
        png_set_packswap(png_ptr);
    #endif

    #ifdef PNG_READ_EXPAND_SUPPORTED
    /* Expand paletted colors into true RGB triplets
     * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
     * Expand paletted or RGB images with transparency to full alpha
     * channels so the data will be available as RGBA quartets.
     */
    if (transforms & PNG_TRANSFORM_EXPAND)
        if ((png_ptr->bit_depth < 8) ||
            (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
            (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
            png_set_expand(png_ptr);
    #endif

    /* We don't handle background color or gamma transformation or quantizing.
     */

    #ifdef PNG_READ_INVERT_SUPPORTED
    /* Invert monochrome files to have 0 as white and 1 as black
     */
    if (transforms & PNG_TRANSFORM_INVERT_MONO)
        png_set_invert_mono(png_ptr);
    #endif

    #ifdef PNG_READ_SHIFT_SUPPORTED
    /* If you want to shift the pixel values from the range [0,255] or
     * [0,65535] to the original [0,7] or [0,31], or whatever range the
     * colors were originally in:
     */
    if ((transforms & PNG_TRANSFORM_SHIFT)
        && png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
    {
        png_color_8p sig_bit;

        png_get_sBIT(png_ptr, info_ptr, &sig_bit);
        png_set_shift(png_ptr, sig_bit);
    }
    #endif

    #ifdef PNG_READ_BGR_SUPPORTED
    /* Flip the RGB pixels to BGR (or RGBA to BGRA)
     */
    if (transforms & PNG_TRANSFORM_BGR)
        png_set_bgr(png_ptr);
    #endif

    #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
    /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR)
     */
    if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
        png_set_swap_alpha(png_ptr);
    #endif

    #ifdef PNG_READ_SWAP_SUPPORTED
    /* Swap bytes of 16 bit files to least significant byte first
     */
    if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
        png_set_swap(png_ptr);
    #endif

    /* Added at libpng-1.2.41 */
    #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
    /* Invert the alpha channel from opacity to transparency
     */
    if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
        png_set_invert_alpha(png_ptr);
    #endif

    /* Added at libpng-1.2.41 */
    #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    /* Expand grayscale image to RGB
     */
    if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
        png_set_gray_to_rgb(png_ptr);
    #endif

    /* We don't handle adding filler bytes */

    /* Optional call to gamma correct and add the background to the palette
     * and update info structure.  REQUIRED if you are expecting libpng to
     * update the palette for you (i.e., you selected such a transform above).
     */
    png_read_update_info(png_ptr, info_ptr);

    /* -------------- image transformations end here ------------------- */

    png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
    if (info_ptr->row_pointers == NULL)
    {
        png_uint_32 iptr;

        info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
                                                        info_ptr->height * png_sizeof(png_bytep));
        for (iptr = 0; iptr < info_ptr->height; iptr++)
            info_ptr->row_pointers[iptr] = NULL;

        info_ptr->free_me |= PNG_FREE_ROWS;

        for (row = 0; row < (int)info_ptr->height; row++)
            info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
                                                                png_get_rowbytes(png_ptr, info_ptr));
    }

    png_read_image(png_ptr, info_ptr->row_pointers);
    info_ptr->valid |= PNG_INFO_IDAT;

    /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);

    transforms = transforms; /* Quiet compiler warnings */
    params = params;

}
        #endif /* PNG_INFO_IMAGE_SUPPORTED */
    #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
#endif /* PNG_READ_SUPPORTED */